Cytometry最新文献

Background: Urine contains microscopically observable particles that can indicate certain types of disease in the urinary tract system. Determining these various types of sediments by manual operation is a cumbersome and time-consuming task. To eliminate this labor, we developed an automated urinary sediment analyzer with high-throughput pretreatment system.

Methods: The pretreatment system mainly consists of four reaction vessels for dying samples (urine), a sheath flow chamber, and an unique sample carrier mechanism from the reaction vessel to the flow chamber, which enables overlapped processing, and rapid transfer of samples with small dispersion and a short buildup time.

Results: The buildup time was experimentally found to be 1.8 s, and the extra-sample volume beside that for measurement was only 4.9 microl (1/20 of the total sample volume).

Conclusions: Short buildup time results in high throughput of 120 samples per hour, and relatively small extra-volume contributes to reduce carryover.

Background: A critical step in automatic microscopy is focusing. This report describes a robust and fast autofocus approach useful for a wide range of microscopic modalities and preparations.

Methods: The focus curve is measured over the complete focal range, reducing the chance that the best focus position is determined by dust or optical artifacts. Convolution with the derivative of a Gaussian smoothing function reduces the effect of noise on the focus curve. The influence of mechanical tolerance is accounted for.

Results: The method is shown to be robust in fluorescence, bright-field and phase contrast microscopy, in fixed and living cells, as well as in fixed tissue. The algorithm was able to focus accurately within 2 or 3 s, even under extremely noisy and low contrast imaging conditions.

Conclusions: The proposed method is generally applicable in light microscopy, whenever the image information content is sufficient. The reliability of the autofocus method allows for unattended operation on a large scale.

We have observed increased numbers of non-neoplastic gammadelta-T-cells in the peripheral blood of a series of patients with non-Hodgkin's lymphoma not of gammadelta-T-cell origin. The majority of normal gammadelta-T-cells are negative for surface CD4 and CD8 and a subpopulation does not express CD5, two immunophenotypic findings strongly suggestive of neoplasia in alpha beta T-cells. In addition, they express cytotoxic T-cell/Natural killer cell antigens. In this study, up to 22% of PBLs were CD4 and CD8 negative gammadelta-T-cells and up to 33% PBLs were CD5 negative gammadelta-T-cells. In addition, as high as 42% of PBLS were gammadelta-T-cells expressing cytotoxic T-cell/Natural killer cell antigens, suggestive of a large granular lymphoproliferative disorder. Failure to recognize that these are normal gammadelta-T-cells could lead to the erroneous diagnosis of peripheral blood involvement with a T-cell neoplasm, especially in the setting of a history of non-Hodgkin's lymphoma. Cytometry (Comm. Clin. Cytometry) 38:280-285, 1999. Published 1999 Wiley-Liss, Inc.

We comparatively assessed CD34+ cell quantification by two of the recently available single platform assays, the IMAGN 2000 STELLer (Immucor, Lisbon, Portugal) microvolume fluorimetry and the ProCOUNT (BD-ENZIfarma, Lisbon, Portugal) flow cytometry, with our "in-house" dual-platform flow cytometric assay. The performance of the methods was evaluated by linearity and reproducibility tests. The linearity study, over a range of 0-1,200 CD34+ cell/microl, gave a good linear relationship for the three methods, with R(2) > 0.99. Precision tested at three different concentrations gave coefficients of variation ranging from 3.6-26.4% for the STELLertrade mark, 2.4-13.8% for the ProCOUNT, and 3.2-6.4% for flow cytometry. CD34+ cells were quantified in umbilical cord blood (UCB), UCB enriched-leukocyte buffy-coat (BC), mobilized peripheral blood (PB) and mobilized peripheral blood progenitor cells (PBPC) collected by leucapheresis, from a total of 72 samples. Flow cytometric results showed good linear correlation to the absolute counts obtained by the STELLer and ProCOUNT for all samples (R > 0.90 for all methods), with no differences when compared by paired tests (P > 0.05). Linear correlations between methods were also found when individually looking at the different cell sources: UCB or PB, BC, and PBPC, with low, intermediate and high CD34+ cell concentrations, respectively. Furthermore, with the exception of a significant difference between the ProCOUNT and STELLer results for UCB (P < 0.05), no other difference between methods was found for each of the individual populations (P > 0.05). To our knowledge, this is the first report in which the results are presented and analyzed according to each source of CD34+ cells. Our results show that the STELLer and the ProCOUNT are equally efficient for the dual-platform flow cytometric assay in CD34+ cell quantification.

Background: Bactericidal application of photosensitizers (PS) is a new and promising area. Up to now the action of PS against bacteria was studied without regard to immunocompetent cells, doses of drugs and radiation being used usually are not safe for such cells and therefore there is still no efficient model for PS application.

Methods: Action of chlorin, a plant derived photosensitizer, on a system of interacting cells and microbes was studied. Cell monitoring was done with a photothermal microscopy method. The two bacteria used were gram-positive (S. aureus) and gram-negative (E. coli) in a mixture of basic blood cells and neutrophils. The latter were used to model phagocytosis as fast cell response reaction.

Results: The strongest bactericidal effect was found when the cells and photoactivated chlorin act together. Selective bactericidal regime of PS application which does not affect cell viability was demonstrated.

Conclusions: The results obtained suggest that this photosensitizer may enhance cell natural defense capabilities.

Background: Image cytometry has proved to provide a good alternative to flow cytometry for DNA ploidy measurement of archival tumors. However, when interactively done this technique is unable to give statistically valuable results within an acceptable time for clinical oncology.

Methods: An image cytometer was developed for fully automatic DNA ploidy quantitation, focusing efforts on speed and accuracy. Software functionalities include systematic acquisition of fields on a microscopic slide, detection, localization and sorting of nuclei, computation of the DNA content together with post-processing tools, for a deeper analysis of the DNA ploidy diagram.

Results: DNA ploidy analysis of archival breast carcinoma samples illustrates the accuracy of DNA ploidy measurements and the sensitivity in the detection of DNA ploidy abnormalities as a result of cell sorting.

Conclusions: Fully automatic image cytometry is able to combine qualities of flow cytometry (automatic analysis of a statistically significant collection of cell nuclei) with additional advantages: sorting of unwanted events (debris, stromal and inflammatory cell nuclei) and facilities for an a posteriori control of the quality of cell selection. This method is well suited to DNA ploidy analysis of archival cancer samples.

Background: A stream-in-air cell sorter enables rapid sorting to a high purity, but it is not well suited for sorting of infectious material due to the risk of airborne spread to the surroundings.

Methods: A FACS Vantage cell sorter was modified for safe use with potentially HIV infected cells. Safety tests with bacteriophages were performed to evaluate the potential spread of biologically active material during cell sorting. Cells transduced with a retroviral vector carrying the gene for GFP were sorted on the basis of their GFP fluorescence, and GFP expression was followed during subsequent culture.

Results: The bacteriophage sorting showed that the biologically active material was confined to the sorting chamber. A failure mode simulating a nozzle blockage resulted in detectable droplets inside the sorting chamber, but no droplets could be detected when an additional air suction from the sorting chamber had been put on. The GFP transduced cells were sorted to 99% purity. Cells not expressing GFP at the time of sorting did not turn on the gene during subsequent culture. Un-sorted cells and cells sorted to be positive for GFP showed a decrease in the fraction of GFP positive cells during culture.

Conclusions: Sorting of live infected cells can be performed safely and with no deleterious effects on vector expression using the modified FACS Vantage instrument.

Background: The alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone (ELF((R))-97 for enzyme-labeled fluorescence) has been found useful for the histochemical detection of endogenous AP activity and AP-tagged proteins and oligonucleotide probes. In this study, we evaluated its effectiveness at detecting endogenous AP activity by flow cytometry.

Methods: The ELF-97 phosphatase substrate was used to detect endogenous AP activity in UMR-106 rat osteosarcoma cells and primary cultures of chick chondrocytes. Cells were labeled with the ELF-97 reagent and analyzed by flow cytometry using an argon ultraviolet (UV) laser. For comparison purposes, cells were also assayed for AP using a Fast Red Violet LB azo dye assay previously described for use in detecting AP activity by flow cytometry.

Results: The ELF-97 phosphatase substrate effectively detected endogenous AP activity in UMR-106 cells, with over 95% of the resulting fluorescent signal resulting from AP-specific activity (as determined by levamisole inhibition of AP activity). In contrast, less than 70% of the fluorescent signal from the Fast Red Violet LB (FRV) assay was AP-dependent, reflecting the high intrinsic fluorescence of the unreacted components. The ELF-97 phosphatase assay was also able to detect very low AP activity in chick chondrocytes that was undetectable by the azo dye method.

Conclusions: The ELF-97 phosphatase assay was able to detect endogenous AP activity in fixed mammalian and avian cells by flow cytometry with superior sensitivity to previously described assays. This work also shows the applicability of ELF-97 to flow cytometry, supplementing its previously demonstrated histochemical applications.